Operating System — Overview

An Operating System (OS) is an interface between a computer user and computer hardware. An operating system is a software which performs all the basic tasks like file management, memory management, process management, handling input and output, and controlling peripheral devices such as disk drives and printers.

Some popular Operating Systems include Linux Operating System, Windows Operating System, VMS, OS/400, AIX, z/OS, etc.

Definition

An operating system is a program that acts as an interface between the user and the computer hardware and controls the execution of all kinds of programs.

Following are some of important functions of an operating System.

• Memory Management
• Processor Management
• Device Management
• File Management
• Security
• Control over system performance
• Job accounting
• Error detecting aids
• Coordination between other software and users

Memory Management

Memory management refers to management of Primary Memory or Main Memory. Main memory is a large array of words or bytes where each word or byte has its own address.

Main memory provides a fast storage that can be accessed directly by the CPU. For a program to be executed, it must in the main memory. An Operating System does the following activities for memory management −

Keeps tracks of primary memory, i.e., what part of it are in use by whom, what part are not in use.

In multiprogramming, the OS decides which process will get memory when and how much.

Allocates the memory when a process requests it to do so.

De-allocates the memory when a process no longer needs it or has been terminated.

Processor Management

In multiprogramming environment, the OS decides which process gets the processor when and for how much time. This function is called process scheduling. An Operating System does the following activities for processor management −

Keeps tracks of processor and status of process. The program responsible for this task is known as traffic controller.

Allocates the processor (CPU) to a process.

De-allocates processor when a process is no longer required.

Device Management

An Operating System manages device communication via their respective drivers. It does the following activities for device management −

Keeps tracks of all devices. Program responsible for this task is known as the I/O controller.

Decides which process gets the device when and for how much time.

Allocates the device in the efficient way.

File Management

A file system is normally organized into directories for easy navigation and usage. These directories may contain files and other directions.

An Operating System does the following activities for file management −

Keeps track of information, location, uses, status etc. The collective facilities are often known as file system.

Decides who gets the resources.

Allocates the resources.

De-allocates the resources.

Other Important Activities

Following are some of the important activities that an Operating System performs −

Security − By means of password and similar other techniques, it prevents unauthorized access to programs and data.

Control over system performance − Recording delays between request for a service and response from the system.

Job accounting − Keeping track of time and resources used by various jobs and users.

Error detecting aids − Production of dumps, traces, error messages, and other debugging and error detecting aids.

Coordination between other softwares and users − Coordination and assignment of compilers, interpreters, assemblers and other software to the various users of the computer systems.

Operating System Version

The Version API Helper functions are used to determine the version of the operating system that is currently running. For more information, see Getting the System Version.

The following table summarizes the most recent operating system version numbers.

Operating system	Version number
Windows 10	10.0*
Windows Server 2019	10.0*
Windows Server 2016	10.0*
Windows 8.1	6.3*
Windows Server 2012 R2	6.3*
Windows 8	6.2
Windows Server 2012	6.2
Windows 7	6.1
Windows Server 2008 R2	6.1
Windows Server 2008	6.0
Windows Vista	6.0
Windows Server 2003 R2	5.2
Windows Server 2003	5.2
Windows XP 64-Bit Edition	5.2
Windows XP	5.1
Windows 2000	5.0

* For applications that have been manifested for Windows 8.1 or Windows 10. Applications not manifested for Windows 8.1 or Windows 10 will return the Windows 8 OS version value (6.2). To manifest your applications for Windows 8.1 or Windows 10, refer to Targeting your application for Windows.

Identifying the current operating system is usually not the best way to determine whether a particular operating system feature is present. This is because the operating system may have had new features added in a redistributable DLL. Rather than using the Version API Helper functions to determine the operating system platform or version number, test for the presence of the feature itself.

To determine the best way to test for a feature, refer to the documentation for the feature of interest. The following list discusses some common techniques for feature detection:

• You can test for the presence of the functions associated with a feature. To test for the presence of a function in a system DLL, call the LoadLibrary function to load the DLL. Then call the GetProcAddress function to determine whether the function of interest is present in the DLL. Use the pointer returned by GetProcAddress to call the function. Note that even if the function is present, it may be a stub that just returns an error code such as ERROR_CALL_NOT_IMPLEMENTED.
• You can determine the presence of some features by using the GetSystemMetrics function. For example, you can detect multiple display monitors by calling GetSystemMetrics(SM_CMONITORS).
• There are several versions of the redistributable DLLs that implement shell and common control features. For information about determining which versions are present on the system your application is running on, see the topic Shell and Common Controls Versions.

If you must require a particular operating system, be sure to use it as a minimum supported version, rather than design the test for the one operating system. This way, your detection code will continue to work on future versions of Windows.

Note that a 32-bit application can detect whether it is running under WOW64 by calling the IsWow64Process function. It can obtain additional processor information by calling the GetNativeSystemInfo function.

Which version of Windows operating system am I running?

Find operating system info in Windows 10

To find out which version of Windows your device is running, press the Windows logo key + R, type winver in the Open box, and then select OK.

Here’s how to learn more:

Select the Start button > Settings > System > About .

Under Device specifications > System type, see if you’re running a 32-bit or 64-bit version of Windows.

Under Windows specifications, check which edition and version of Windows your device is running.

Related links

If you’re having a problem with activation, see Activate in Windows 10.

If you forgot the password you use to sign in to Windows devices or email, see How to reset your Microsoft password.

For info about updating Windows, see Windows Update: FAQ.

Find operating system info in Windows 8.1 or Windows RT 8.1

To find out which version of Windows your device is running, press the Windows logo key + R, type winver in the Open box, and then select OK.

If your device is running Windows 8.1 or Windows RT 8.1, here’s how to learn more:

If you’re using a touch device, swipe in from the right edge of the screen, tap Settings, and then tap Change PC settings. Continue to step 3.

If you’re using a mouse, point to the lower-right corner of the screen, move the mouse pointer up, click Settings, and then click Change PC settings.

Select PC and devices > PC info.

Under Windows you’ll see which edition and version of Windows your device is running.

Under PC > System type you’ll see if you’re running a 32-bit or 64-bit version of Windows.

Related links

If you’re having a problem with activation, see Activate Windows 7 or Windows 8.1

If you forgot the password you use to sign in to Windows devices or email, see How to reset your Microsoft password.

For info about updating Windows, see Windows Update: FAQ.

Find operating system info in Windows 7

Select the Start button, type Computer in the search box, right-click on Computer, and then select Properties.

Under Windows edition, you’ll see the version and edition of Windows that your device is running.

Support for Windows 7 ended on January 14, 2020

We recommend you move to a Windows 10 PC to continue to receive security updates from Microsoft.

Related links

If you’re having a problem with activation, see Activate Windows 7 or Windows 8.1.

If you forgot the password you use to sign in to Windows devices or email, see How to reset your Microsoft password.

For info about updating Windows, see Windows Update: FAQ.

Microsoft Windows

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Microsoft Windows, also called Windows and Windows OS, computer operating system (OS) developed by Microsoft Corporation to run personal computers (PCs). Featuring the first graphical user interface (GUI) for IBM-compatible PCs, the Windows OS soon dominated the PC market. Approximately 90 percent of PCs run some version of Windows.

The first version of Windows, released in 1985, was simply a GUI offered as an extension of Microsoft’s existing disk operating system, or MS-DOS. Based in part on licensed concepts that Apple Inc. had used for its Macintosh System Software, Windows for the first time allowed DOS users to visually navigate a virtual desktop, opening graphical “windows” displaying the contents of electronic folders and files with the click of a mouse button, rather than typing commands and directory paths at a text prompt.

Subsequent versions introduced greater functionality, including native Windows File Manager, Program Manager, and Print Manager programs, and a more dynamic interface. Microsoft also developed specialized Windows packages, including the networkable Windows for Workgroups and the high-powered Windows NT, aimed at businesses. The 1995 consumer release Windows 95 fully integrated Windows and DOS and offered built-in Internet support, including the World Wide Web browser Internet Explorer.

With the 2001 release of Windows XP, Microsoft united its various Windows packages under a single banner, offering multiple editions for consumers, businesses, multimedia developers, and others. Windows XP abandoned the long-used Windows 95 kernel (core software code) for a more powerful code base and offered a more practical interface and improved application and memory management. The highly successful XP standard was succeeded in late 2006 by Windows Vista, which experienced a troubled rollout and met with considerable marketplace resistance, quickly acquiring a reputation for being a large, slow, and resource-consuming system. Responding to Vista’s disappointing adoption rate, Microsoft in 2009 released Windows 7, an OS whose interface was similar to that of Vista but was met with enthusiasm for its noticeable speed improvement and its modest system requirements.

Windows 8 in 2012 offered a start screen with applications appearing as tiles on a grid and the ability to synchronize settings so users could log on to another Windows 8 machine and use their preferred settings. In 2015 Microsoft released Windows 10, which came with Cortana, a digital personal assistant like Apple’s Siri, and the Web browser Microsoft Edge, which replaced Internet Explorer. Microsoft also announced that Windows 10 would be the last version of Windows, meaning that users would receive regular updates to the OS but that no more large-scale revisions would be done.

The Editors of Encyclopaedia Britannica This article was most recently revised and updated by Amy Tikkanen, Corrections Manager.

Windows (operating system)

Windows is a series of operating systems produced and maintained by the Microsoft Corporation. It was estimated that as of December 2007 [1] Microsoft Windows accounted for nearly 90% of operating system usage, with 3 out of 4 being Windows XP. Windows is used for desktop, and server computers, [2] and more recently also for cellular phones and tablet computers. It is intended for use with the Intel x86-64 family of processors.

Early versions of Windows (98 and earlier) were notoriously unreliable, despite (or maybe because of?) Microsoft’s near-monopoly share of the operating system market. They crashed so often that the term «blue screen of death» entered the vocabulary. See also this satire: Matrix Runs on Windows XP

Initially Windows was a text-based system (MS-DOS). Then a Graphical User Interface extension was added onto this MS-DOS core [3] It became a full GUI operating system free of the MS-DOS core beginning with the release of Windows NT.

Contents

Windows Major Release Versions

Professional: 650MB
Server and Advanced Server: 1GB [11]

Name	Version Number	Public Release	Notes	Editions	Minimum RAM required	Minimum drive space
Windows 1.0	1.0	November 20, 1985 [4]	Sold 500,000 copies [5]
Windows 1.02	1.02	May 1986	Multilingual (international) release of 1.0
Windows 1.03	1.03	August 1986	Further upgrades for international use, including more drivers and European keyboard support
Windows 1.04	1.04	April 1987	Further functionality additions, including support for IBM PS/2 computers
Windows 2.0	2.11	March 13, 1989	Last Windows version to run a GUI as a shell over a base of MS-DOS [6] Sold 1 million copies
Windows 3.0	NT 3.0	May 22, 1990	First Windows version to run without an MS-DOS base [6] Sold 4 million copies
Windows 3.1	3.1	April 1992	First MS operating system on CD-ROM	Windows 3.1 Windows for Workgroups 3.1 (October 1992)	1MB	i286 15MB
Windows 3.2	November 22, 1993	Chinese version of Windows 3.1
Windows NT 3.5	3.5.807	September 21, 1994	Workstation Server
Windows NT 3.51	3.51.1057	May 30, 1995	An operating system design that led to the elimination of Novell Networks leading market share. This New Technologies (NT) kernel became the basis for all future Windows versions through Windows 10.	Workstation Server
Windows 95	NT 4.0.950	August 24, 1995	Uses the same skin as 98, 2000, and ME	4MB [7]	40.8-76.2MB [8]
Windows NT 4.0	NT 4.0	July 29, 1996	Workstation Server Server Enterprise Terminal Server
Windows CE Alder [9]	CE 1.0	November 16, 1996 [9]	2MB
Windows CE Birch [9]	CE 2.0	November 1997 [9]	Auto PC platform introduced [10]
Windows 98	NT 4.1.1998	June 25, 1998	Uses the same skin as 95, 2000, and ME	16MB	500MB
Windows 98 Second Edition	NT 4.1.2222	April 23, 1999	Uses the same skin as 95, 2000, and ME
Windows CE 2.1
Windows 2000	NT 5.0.2195	February 17, 2000	Uses the same skin as 95, 98, and ME Last dedicated operating system for business use	Professional Server Advanced Server Datacenter Server Xbox Xbox 360
Windows CE Cedar	CE 3.0	April 2000	Windows CE for Automotive
Windows ME	NT 4.90.3000	September 14, 2000	Uses the same skin as 95, 98, and 2000 Last dedicated operating system for personal use
Windows XP	5.1.2600	October 25, 2001	Last major version to use this layout, which was introduced with Windows 95 XP was the beginning of one unified O/S for both personal and business use. Only one version is still supported by Microsoft, XP Embedded until January 2019. Sold 400 million copies	Starter Home Professional Professional x64 Media Center 2002 Media Center 2004 Media Center 2005 Tablet PC Embedded	x32/x86: 64MB [12] x64: 256MB	1.5GB
Windows CE Talisker [9]	CE 4.0	January 7, 2002
Windows CE Jameson [9]	CE 4.1	June 2002 [9]	Windows Automotive
Windows CE McKendric [9]	CE 4.2	April 2003 [9]	Windows Automotive 4.2
Windows Server 2003	NT 5.2	2003
Windows CE Macallan [9]	CE 5.0	August 2004 [9]	Windows Automotive 5.0	6MB [13]
Windows Server 2003 R2	2006
Windows CE Yamazaki [9]	CE 6.0	September 2006 [9]	Microsoft Auto 3.0 Zune HD
Windows Vista	NT 6.0.6000	January 30, 2007	System uses new layout, but started out with some problems Sold 180 million copies Extended support ends April 11, 2017 [14]	Starter Home Basic Home Premium Business Ultimate Enterprise	Home Basic: 512MB, All Others: 1GB [15]	20GB
Windows Server 2008	February 27, 2008	512 MB	Foundation: 10GB, other x32/86: 20GB, other x64: 32GB
Windows 7	NT 6.1.7600	October 22, 2009	Uses the same basic layout as Vista, but system is more stable Sold 600 million copies Extended support ends January 14, 2020	Starter Home Basic Home Premium Professional Enterprise Ultimate Thin PC	x32/x86: 1GB, x64: 2GB [12]	x32/x86: 16GB, x64: 20GB
Windows Server 2008 R2	2010	HPC Standard Enterprise Itanium	512 MB	Foundation: 10GB, others: 32GB
Windows Embedded Compact 7	CE 6.0 R3	2011	Windows Embedded Automotive 7 Windows Phone 7
Windows Server 2012	NT 6.2	2012	Foundation Essentials Standard Datacenter	512MB	32GB
Windows 8	NT 6.2	October 26, 2012	Designed to serve as an OS for all kinds of devices, including smartphones Also did away with the Start menu Sold surprisingly poorly Extended support ends January 10, 2023	Standard Professional Enterprise Embedded	x32/x86: 1GB, x64: 2GB [16]	x32/x86: 16GB, x64: 20GB
Windows RT	NT 6.3	October 30, 2012	Designed exclusively for ARMv7 processors Based on Windows 8 without an upgrade path to Windows 10 Support already phasing out	Embedded	32-Bit: 2GB [16]	32-Bit: 20GB, 32GB
Windows Server 2012 R2	NT 6.3	2013	Foundation Essentials Standard Datacenter	512MB	32GB
Windows 8.1	NT 6.3	October 17, 2013	Slight update from 8.0 which brings back the Start button	Standard Professional Enterprise Embedded	x32/x86: 1GB, x64: 2GB [16]
Windows 10	NT 6.4 [17]	July 29, 2015	Designed to collect personal information and customize itself based on preferences 270 million copies of version 10 are in use as of March 2016. [18] Extended support ends October 14, 2025	Home Professional Enterprise Education Mobile Mobile Enterprise IoT Core Xbox One	x32/x86: 1GB, x64: 2GB [19]	x32/x86: 16GB, x64: 20GB [20][21]
Windows Server 2016	October 12, 2016 (RTM: September 26, 2016)	Essentials Standard Datacenter
Name	Version Number	Public Release	Notes	Editions	Minimum RAM required	Minimum drive space

(Some popular NT releases are listed in bold and special server releases are listed in italic.) [22] [23] [24] [25]